Method for transmitting or receiving signal in wireless communication system and apparatus therefor

ABSTRACT

A method for receiving, by a terminal, downlink control information in a wireless communication system according to one embodiment of the present invention comprises the steps of: receiving information on a reference subcarrier spacing (SCS) from among a plurality of SCS numerologies; receiving downlink control information through a terminal group common physical downlink control channel (PDCCH); and obtaining information on a slot format from the downlink control information, wherein the downlink control information indicates the slot format on the basis of the reference SCS, and when the SCS of the terminal is different from the reference SCS, the terminal may convert the slot format of the reference SCS according to the SCS of the terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/064,723, filed on Jun. 21, 2018, which claims the benefit ofInternational Application No. PCT/KR2018/003465, filed on Mar. 23, 2018,which claims the benefit of U.S. Provisional Application No. 62/621,495,filed on Jan. 24, 2018, U.S. Provisional Application No. 62/616,450,filed on Jan. 12, 2018, U.S. Provisional Application No. 62/596,785,filed on Dec. 9, 2017, U.S. Provisional Application No. 62/500,557,filed on May 3, 2017, and U.S. Provisional Application No. 62/476,682,filed on Mar. 24, 2017. The disclosures of the prior applications areincorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method and apparatus for transmitting orreceiving downlink (DL) control information in a wireless communicationsystem.

BACKGROUND ART

First, the existing 3GPP LTE/LTE-A system will be briefly described.Referring to FIG. 1, the UE performs an initial cell search (S101). Inthe initial cell search process, the UE receives a PrimarySynchronization Channel (P-SCH) and a Secondary Synchronization Channel(S-SCH) from a base station, performs downlink synchronization with theBS, and acquires information such as a cell ID. Thereafter, the UEacquires system information (e.g., MIB) through a PBCH (PhysicalBroadcast Channel). The UE can receive the DL RS (Downlink ReferenceSignal) and check the downlink channel status.

After the initial cell search, the UE can acquire more detailed systeminformation (e.g., SIBs) by receiving a Physical Downlink ControlChannel (PDCCH) and a Physical Downlink Control Channel (PDSCH)scheduled by the PDCCH (S102).

The UE may perform a random access procedure for uplink synchronization.The UE transmits a preamble (e.g., Msg1) through a physical randomaccess channel (PRACH) (S103), and receives a response message (e.g.,Msg2) for the preamble through PDCCH and PDSCH corresponding to thePDCCH. In the case of a contention-based random access, a contentionresolution procedure such as additional PRACH transmission (S105) andPDCCH/PDSCH reception (S106) may be performed.

Then, the UE can perform PDCCH/PDSCH reception (S107) and PhysicalUplink Shared Channel (PUSCH)/Physical Uplink Control Channel (PUCCH)transmission (S108) as a general uplink/downlink signal transmissionprocedure. The UE can transmit UCI (Uplink Control Information) to theBS. The UCI may include HARQ ACK/NACK (Hybrid Automatic Repeat reQuestAcknowledgment/Negative ACK), SR (Scheduling Request), CQI (ChannelQuality Indicator), PMI (Precoding Matrix Indicator) and/or RI etc.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method and apparatus for more effectively and accurately indicating aslot format through downlink (DL) control information in a wirelesscommunication system for supporting multiple subcarrier spacing (SCS).

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Technical Solution

The object of the present invention can be achieved by providing amethod of receiving downlink (DL) control information by a userequipment (UE) in a wireless communication system, the method includingreceiving information on reference subcarrier spacing (SCS) among aplurality of SCS numerologies, receiving DL control information througha UE group common physical downlink control channel (PDCCH), andacquiring information on a slot format from the DL control information,wherein the DL control information indicates the slot format based onthe reference SCS, and wherein, when SCS of the UE is different from thereference SCS, the UE converts a slot format of the reference SCSaccording to the SCS of the UE.

In another aspect of the present invention, provided herein is a userequipment (UE) for receiving downlink (DL) control information,including a receiver, and a processor configured to control the receiverto receive information on reference subcarrier spacing (SCS) among aplurality of SCS numerologies, to receive DL control information througha UE group common physical downlink control channel (PDCCH), and toacquire information on a slot format from the DL control information,wherein the DL control information indicates the slot format based onthe reference SCS, and wherein, when SCS of the UE is different from thereference SCS, the processor converts a slot format of the reference SCSaccording to the SCS of the UE.

In another aspect of the present invention, provided herein is a methodof transmitting downlink (DL) control information by a base station (BS)in a wireless communication system, the method including transmittinginformation on reference subcarrier spacing (SCS) among a plurality ofSCS numerologies, generating DL control information includinginformation on a slot format, and transmitting the DL controlinformation to a UE group including the UE through a UE group commonphysical downlink control channel (PDCCH), wherein, even if the SCS ofthe UE is different from the reference SCS, the BS notifies the UE aboutthe slot format based on the reference SCS.

In another aspect of the present invention, provided herein is a basestation (BS) for performing the aforementioned DL control informationtransmitting method.

The information on the reference SCS may be received via higher layersignaling.

Time duration of 1 slot may be variable depending on SCS, and thereference SCS may be configured to be equal to or less than the SCS ofthe UE such that time duration of 1 slot based on the reference SCS isequal to or greater than time duration of 1 slot based on the SCS of theUE.

When the SCS of the UE is M times the reference SCS, the UE mayinterpret 1 slot based on the reference SCS as M contiguous slots basedon the SCS of the UE.

The UE may determine, based on the information on the slot format,whether each of a plurality of symbols included in a corresponding slotcorresponds to downlink (D), uplink (U), or flexible (X); and, wherein,when the SCS of the UE is M times the reference SCS, the UE mayinterpret one D, U, or X symbol based on the reference SCS as M numberof D, U, or X symbols based on the SCS of the UE.

The information on the slot format may indicate at least one of slotformation combinations configured in the UE.

The UE may be configured with a plurality of frequency bands and eachslot format combination may be a combination of a plurality of slotformats of the plurality of frequency bands.

The each slot format combination is a combination of a slot format for aDL frequency band and a slot format for a UL frequency band.Alternatively, wherein the each slot format combination may be acombination of a slot format for a new radio access technology (NR)frequency band and a slot format for a long-term evolution (LTE)frequency band.

The slot formation combinations configured in the UE may be received viahigher layer signaling and may be a subset of a plurality of slot formatcombinations supported in the wireless communication system.

Advantageous Effects

According to an embodiment of the present invention, referencesubcarrier spacing (SCS) is configured in a wireless communicationsystem in which multiple SCS is supportable to accurately interpret aslot format and a slot format may be signaled UE-group commonly based onthe reference SCS and, thus, a payload size of a physical downlinkcontrol channel (PDCCH) may be reduced and overhead of the PDCCH may bereduced compared with the case in which a slot format is indicated foreach separate SCS.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates physical channels used in a 3GPP LTE/LTE-A system anda general signal transmission method using the physical channels.

FIG. 2 illustrates 1 slot based on subcarrier spacing (SCS) of 15 kHzand 1 slot based on SCS of 60 kHz.

FIG. 3 illustrates combinations of slot formats according to anembodiment of the present invention.

FIG. 4 illustrates combinations of slot formats according to anotherembodiment of the present invention.

FIGS. 5 and 6 illustrate combinations of slot formats according toanother embodiment of the present invent.

FIG. 7 illustrates a combination of slot formats according to anembodiment of the present invention.

FIG. 8 illustrates patterns of slot formats according to an embodimentof the present invention.

FIG. 9 illustrates reserved resource allocation for a group commonphysical downlink control channel (PDCCH) according to an embodiment ofthe present invention.

FIG. 10 illustrates a GSS deployed in a CSS according to an embodimentof the present invention.

FIG. 11 illustrates GSS candidates having a fixed position in a CSSaccording to an embodiment of the present invention.

FIGS. 12 and 13 illustrate slot patterns of multiple CCs according to anembodiment of the present invention.

FIG. 14 illustrates slot patterns of multiple CC according to anotherembodiment of the present invention.

FIG. 15 illustrates a flow of a method of transmitting and receivingdownlink control information (DCI) according to an embodiment of thepresent invention.

FIG. 16 illustrates a base station (BS) and a user equipment (UE)according to an embodiment of the present invention.

MODE FOR INVENTION

The following description of embodiments of the present invention mayapply to various wireless access systems including CDMA (code divisionmultiple access), FDMA (frequency division multiple access), TDMA (timedivision multiple access), OFDMA (orthogonal frequency division multipleaccess), SC-FDMA (single carrier frequency division multiple access) andthe like. CDMA can be implemented with such a radio technology as UTRA(universal terrestrial radio access), CDMA 2000 and the like. TDMA canbe implemented with such a radio technology as GSM/GPRS/EDGE (GlobalSystem for Mobile communications)/General Packet Radio Service/EnhancedData Rates for GSM Evolution). OFDMA can be implemented with such aradio technology as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, E-UTRA (Evolved UTRA), etc. UTRA is a part of UMTS (UniversalMobile Telecommunications System). 3GPP (3rd Generation PartnershipProject) LTE (long term evolution) is a part of E-UMTS (Evolved UMTS)that uses E-UTRA. 3GPP LTE adopts OFDMA in downlink and adopts SC-FDMAin uplink. LTE-A (LTE-Advanced) is an evolved version of 3GPP LTE.

For clarity, the following description mainly concerns 3GPP LTE systemor 3GPP LTE-A system, by which the technical idea of the presentinvention may be non-limited. Specific terminologies used in thefollowing description are provided to help understand the presentinvention and the use of the terminologies can be modified to adifferent form within a scope of the technical idea of the presentinvention.

As many as possible communication devices have demanded as high ascommunication capacity and, thus, there has been a need for enhancedmobile broadband (eMBB) communication compared with legacy radio accesstechnology (RAT) in a recently discussed next-generation communicationsystem. In addition, massive machine type communications (mMTC) forconnecting a plurality of devices and objects to provide variousservices anytime and anywhere is also one of factors to be considered innext-generation communication. In addition, in consideration of aservice/user equipment (UE) that is sensitive to reliability andlatency, ultra-reliable and low latency communication (URLLC) has beendiscussed for a next-generation communication system.

As such, new RAT that considers eMBB, mMTC, URLCC, and so on has beendiscussed for next-generation wireless communication.

Some LTE/LTE-A operations and configuration that are not at variance toa design of New RAT may also be applied to new RAT. For convenience, newRAT may be referred to as 5G mobile communication.

<NR Frame Structure and Physical Resource>

In an NR system, downlink (DL) and downlink (UL) transmission may beperformed through frames having duration of 10 ms and each frame mayinclude 10 subframes. Accordingly, 1 subframe may correspond to 1 ms.Each frame may be divided into two half-frames.

1 subframe may include N_(symb) ^(subframe,μ)=N_(symb) ^(slot)×N_(slot)^(subframe,μ) contiguous OFDM symbols. N_(symb) ^(slot) represents thenumber of symbols per slot, μ represents OFDM numerology, and N_(slot)^(subframe,μ) represents the number of slots per subframe with respectto corresponding μ. In NR, multiple OFDM numerologies shown in Table 1below may be supported.

TABLE 1 μ Δf = 2^(μ) · 15[kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

In Table 1 above, Δf refers to subcarrier spacing (SCS). μ and cyclicprefix with respect to a DL carrier bandwidth part (BWP) and μ andcyclic prefix with respect to a UL carrier BWP may be configured for aUE via UL signaling.

Table 2 below shows the number of N_(symb) ^(slot) of symbols per slot,the number N_(slot) ^(frame,μ) of symbols per frame, and the numberN_(slot) ^(subframe,μ) of slots per subframe with respect to each SCS inthe case of normal CP.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16 5 14 32 32

Table 3 below shows the number N_(symb) ^(slot) of symbols per slot, thenumber N_(slot) ^(frame,μ) of slots per frame, and the number N_(slot)^(subframe,μ) of slots per subframe with respect to each SCS in the case of extended CP.

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

As such, in an NR system, the number of slots included in 1 subframe maybe variable depending on subcarrier spacing (SCS). OFDM symbols includedin each slot may correspond to any one of D (DL), U (UL), and X(flexible). DL transmission may be performed in a D or X symbol and ULtransmission may be performed in a U or X symbol. A Flexible resource(e.g., X symbol) may also be referred to as a Reserved resource, anOther resource, or a Unknown resource.

In NR, one resource block (RB) may correspond to 12 subcarriers in thefrequency domain. A RB may include a plurality of OFDM symbols. Aresource element (RE) may correspond to 1 subcarrier and 1 OFDM symbol.Accordingly, 12 REs may be present on 1 OFDM symbol in 1 RB.

A carrier BWP may be defined as a set of contiguous physical resourceblocks (PRBs). The carrier BWP may also be simply referred to a BWP. Amaximum of 4 BWPs may be configured for each of UL/DL link in 1 UE. Evenif multiple BWPs are configured, 1 BWP may be activated for a given timeperiod. However, when a supplementary uplink (SUL) is configured in aUE, 4 BWPs may be additionally configured for the SUL and 1 BWP may beactivated for a given time period. A UE may not be expected to receive aPDSCH, a PDCCH, a channel state information-reference signal (CSI-RS),or a tracking reference signal (TRS) out of the activated DL BWP. Inaddition, the UE may not be expected to receive a PUSCH or a PUCCH outof the activated UL BWP.

<NR DL Control Channel>

In an NR system, a transmissions NR system, a transmission unit of acontrol channel may be defined as a resource element group (REG) and/ora control channel element (CCE), etc.

An REG may correspond to 1 OFDM symbol in the time domain and maycorrespond to 1 PRB in the frequency domain. In addition, 1 CCE maycorrespond to 6 REGs.

A control resource set (CORESET) and a search space (SS) are brieflydescribed now. The CORESET may be a set of resources for control signaltransmission and the search space may be aggregation of control channelcandidates for perform blind detection. The search space may beconfigured for the CORESET. For example, when one search space isdefined on one CORESET, a CORESET for a common search space (CSS) and aCORESET for a UE-specific search space (USS) may each be configured. Asanother example, a plurality of search spaces may be defined in oneCORESET. For example, the CSS and the USS may be configured for the sameCORESET. In the following example, the CSS may refer to a CORESET with aCSS configured therefor and the USS may refer to a CORESET with a USSconfigured therefor, or the like.

A base station may signal information on a CORESET to a UE. For example,a CORESET configuration for each CORESET and time duration (e.g., 1/2/3symbol) of the corresponding CORESET may be signaled. When interleavingfor distributing a CCE to 1 symbol-CORESET is applied, 2 or 6 REGs maybe bundled. Bundling of 2 or 6 REGs may be performed on 2 symbol-CORESETand time-first mapping may be applied. Bundling of 3 or 6 REGs may beperformed on 3 symbol-CORESET and time-first mapping may be applied.When REG bundling is performed, the UE may assume the same precodingwith respect to a corresponding bundling unit.

<Slot Format Indication>

A slot type and an operating method of a UE when a guard period (GP) ismaintained or changed are described now. In addition, a method ofhandling slot type indication when numerology of a slot type is changedand methods of indicating reserved resources are described below. A slottype may be referred to as a slot format.

1. Slot Type Indication

A UE may receive information on a slot type. The information on the slottype may indicate a slot type and may include information on, forexample, a downlink pilot time slot (DwPTS), a uplink pilot time slot(UpPTS), a guard period (GP), and a reserved resource.

The information on the slot type may be periodically or aperiodicallytransmitted. Whether the received slot type indication information isapplied may be determined by the UE or may be forcibly applied.

For example, the information on the slot type may be received through aPDCCH. For example, the information on the slot type may be receivedthrough a common PDCCH or may also be received through UE-specificcontrol information (e.g., DCI).

The information on the slot type received through the common PDCCH maybe control information for collectively indicating a slot type to aspecific UE group or all UEs in a cell. The information on the slot typereceived through the UE-specific PDCCH may be control informationindicating a slot type of each UE.

2. Guard Period (GP)

(1) GP Based on Slots, all of which are Configured in DL or UL

A GP may be defined according to an end position of a DwPTS and a startposition of an UpPTS.

The GP may be positioned subsequent to the DwPTS. The end position ofthe DwPTS may be transmitted to a UE through a common PDCCH. Forexample, the UE may calculate the GP based on the transmitted endposition of the DwPTS, and the UpPTS and the UL slot in whichtransmission is to be performed. Separately, indication of the GP may besignaled to the UE.

The GP may be positioned before the UpPTS. The UE may receiveinformation on a start position of the UpPTS through the common PDCCH.The UE may use the start position of the UpPTS as an end position of theGP without change or the UE may determine the end position of the GPbased on the start position of the UpPTS.

The GP may be present only in a slot or may be present between slots.The position and length of the GP may not be limited. It may be possiblethat the GP is present over between slots when a DL slot and a UL slotare contiguously present. For example, the GP may be present between aDL slot and a UL slot.

A method of forming a GP for each UE or for each UE group may beconfigured. Configuration of the GP may be cell-common or may bepredefined.

Each UE or UE group may be configured with a GP and, in this case,greater or fewer cell-specific GPs may be configured than GPs signaledto each UE or UE group. For example, when the number of GPs of the UE isless than cell-specific or group common GPs, an additional resource maybe used as a GP according to dynamic indication and, when the number ofGPs of the UE is greater than the cell-specific or group common GPs, anadditional GP may be formed according to a predetermined rule.

(i) When GP is Maintained Constant

A GP of a UE may be maintained constant and may not be affected by acommon PDCCH after the GP is configured once. For example, a cell-commonor group common GP transmitted in a system information block (SIB) orthe like may not be changed by a common PDCCH. In addition, indicationof a GP in the common PDCCH may be omitted.

For example, when a GP is 5-symbol and one slot is 14-symbol, D, U, orreserved with respect to 9 symbols may be indicated. In addition, the GPmay be configured for each subframe or for each slot set. The GPconfiguration may be given as fallback configuration. For example, theGP configured in fallback may always be assumed with respect to a commonPDCCH. Fixed DL, UL, GP, or reserved, configured in fallback, may beassumed and, thus, corresponding indication may be omitted from thecommon PDCCH.

(ii) When GP is Changeable by Common PDCCH

A GP of a UE may be changeable by a common PDCCH. There may be noproblem when the UE normally receives the common PDCCH but there may bea problem in terms of GP configuration when the common PDCCH is notcapable of being received.

Accordingly, a network needs to notify the UE about a minimum GP and amaximum GP which are supported by a cell. The minimum GP may be definednot to be changed by the common PDCCH. For example, the minimum GP maybe 0.

a. Fallback Operation when Common PDCCH is Missed

Upon determining that slot type indication is not received by the UE oris not transmitted, the UE may maintain a most recently indicated slottype.

In addition, when a specific slot type is preconfigured to the UE viasemi-static signaling and the UE misses slot type indication or is notcapable of receiving the slot type indication, a slot typepre-configured via semi-static signaling may be used.

GPs of best/worst cases, used for fallback, may be defined. When acommon PDCCH is defined to indicate the best GP, a GP signaled forfallback may also be configured as the best GP. When the common PDCCH isdefined to indicate the worst GP, a GP signaled for fallback may also beconfigured as the worst GP.

A GP of the best/worst case GP, which is applied for fallback, may bepredefined or may be configured by a network. This may be required todefine an operation of the UE when fallback configuration is applied.

(2) when all UEs in Cell Use the Same GP

An environment in which all UEs in a cell use the same GP may beconsidered. A size of a DwPTS in which a UE receives a signal and a sizeof an UpPTS in which the UE transmits a signal may be the same withrespect to all UEs or may be different for the UEs.

When a size of DwPTS/UpPTS is different for each UE, a PTS of each UEmay be configured to be sufficiently put in a slot type indicated by thePTS. For example, even if a size of DwPTS/UpPTS is different for eachUE, the size of DwPTS/UpPTS of all UEs may be a size of a PTS in whichUL/DL transmission and reception are enabled without change in a slottype indicated UE-group commonly. Alternatively, in reality, the size ofthe DwPTS/UpPTS of the all UEs may be the same.

(3) When GP is Different for Each UE

An environment in which all UEs in a cell are capable of using differentGPs may be considered. A size of a DwPTS in which a UE receives a signaland a size of a UpPTS in which the UE transmits a signal may be the samefor the all UEs or may be different for each UE.

Upon notifying UEs about GP information through a common PDCCH, anetwork may configure end positions of DwPTSs of all UEs to be the same.For example, an end position of the DwPTS may be the latest point, theearliest point, or the intermediate point among the end points of theDwPTS of UEs in a cell.

(i) When Latest End Point of DwPTS is Indicated

The end position of the DwPTS indicated by the network may be the latestpoint among end points of the DwPTSs of UEs in a cell. Accordingly, anend position of a DwPTS of a specific UE may be earlier than the endposition of the DwPTS indicated through the common PDCCH. In this case,the UE may first terminate DL reception and, thus, may further transmitUL data by an ensured time period or may transmit UL data only in anUpPTS.

(ii) When Earliest End Point of DwPTS is Indicated

The end position of the DwPTS indicated by the network may be theearliest point among end points of the DwPTSs of UEs in a cell.Accordingly, an end position of a DwPTS of a specific UE may be laterthan the end position of the DwPTS indicated through the common PDCCH.In this case, when a start position of a UpPTS of a UE is within a GP,the corresponding UE may transmit an UpPTS in UL without change and,when the start position of the UpPTS is not within the GP, the UE mayshorten the UpPTS and transmit the UpPTS in UL or may skip ULtransmission on the corresponding UpPTS.

(iii) When End Position of Average DwPTS is Indicated

The end position of the DwPTS indicated by the network may be an averagepoint among end points of the DwPTSs of UEs in a cell. Accordingly, anend position of a DwPTS of a specific UE may be later or earlier thanthe end position of the DwPTS indicated through the common PDCCH. Inconsideration of this situation, two UpPTS types may be defined to ashort UpPTS and a long UpPTS and the UE may prepare transmission withrespect to two UpPTS types.

3. Handling of Different Numerologies and Slot Sizes

When numerology of a DwPTS, an UpPTS, or the like, which is transmittedand received by a UE, is changed, a slot size may also be changed.According to whether a slot type indicated through a common PDCCH isindicated based on numerology that is currently used by the UE or isindicated based on reference numerology, an operation of the UE and aused slot may be changed.

For example, the reference numerology as a reference for indication of aslot type may be defined/configured. When the slot type is indicatedbased on the reference numerology, the UE may change and interpret theindicated slot type according to numerology used by the UE. The UE maychange a slot size indicated based on the reference numerology by thecommon PDCCH to a slot size corresponding to numerology used by the UEand may apply the changed slot size.

As another example, when a network indicates a slot type, the networkmay indicate a slot type according to numerology used by the UE. In thiscase, the UE may apply the slot type indicated by the network withoutchange rather than separately calculating a slot size.

4. Periodic Resource Configuration

Among resources required to maintain connection of a UE with a network,there may be resources that are not clearly defined or a slot type ofwhich is not defined. To use such resources, the network may signal aconfiguration of corresponding resources using a common PDCCH or maybasically define a static configuration with respect to use of thecorresponding resources.

(1) CSI-RS

To receive a CSI-RS by the UE, the following methods may be considered.

(i) For example, the UE may be defined to always receive a periodicCSI-RS. Without separate indication for CSI-RS reception, the UE mayassume that the periodic CSI-RS is always transmitted by a network andmay operate.

(ii) As another example, the UE may pre-knows candidate resources inwhich a periodic CSI-RS is to be transmitted and the network may notifythe UE about whether a CSI-RS is actually transmitted to a correspondingresource through the common PDCCH. In this case, load may be reducedcompared with the case in which the UE always receives the CSI-RS butthe UE needs to appropriately receive the common PDCCH to receive theCSI-RS.

The network may also configure the methods (i) and (ii) according to achannel situation.

For example, the CSI-RS may be classified into two types. The networkmay distinguish between a guaranteed CSI-RS in which transmission isensured and a potential CSI-RS in which transmission is to be enabledand may transmit a CSI-RS configuration. The guaranteed CSI-RS may bealways transmit without indication through a common PDCCH andtransmission of the potential CSI-RS may be activated through a commonPDCCH or other control signals.

The guaranteed CSI-RS may be used for periodic CSI report and thepotential CSI-RS may also be used for aperiodic CSI report that istriggered as necessary.

Both the guaranteed CSI-RS and the potential CSI-RS may be used forperiodic/aperiodic CSI measurement.

Alternatively, the UE may selectively use the two types of CSI-RSsaccording to the cases.

(2) Grand-Free Resource

In NR, a grant-free resource in which a UE performs UL transmissionwithout reception of DCI corresponding to UL grant may be configured.

For example, there may be an always grant-free resource that is alwaysused as a grant-free resource and a flexible grant-free resource that isconfigured as a grant-free resource according to dynamic indicationthrough a common PDCCH.

Even if the UE does not receive indication of a flexible resource, theUE may use the always grant-free resource.

For example, the always grant-free resource may assist the flexiblegrant-free resource.

In a state in which the UE pre-knows candidates of all grant-freeresources, the network may indicate the grant-free resource that is tobe used by the corresponding UE through a common PDCCH. In this case,upon appropriately receiving the common PDCCH, there may be a limit inthat the UE is capable of using the grant-free resource but thegrant-free resource in a system may be minimized.

The network may determine a UE group that is capable of attempting toaccess every grant-free resource and may also notify only thecorresponding group about the grant-free resource through the commonPDCCH. In this case, the common PDCCH may include identificationinformation on UE(s) that is capable of accessing the correspondinggrant-free resource.

The UE that is capable of accessing the corresponding grant-freeresource may be determined according to priority. For example, thepriority may be determined based on a rate of failure to the number oftimes of access attempts or may be determined based on the size/urgentdegree of UL data to be transmitted.

Such a method of configuring always (or fixed)/flexible resources mayalso be applied to a semi-static resource such as a radio resourcemanagement-reference signal (RRM-RS) resource, a random access channel(RACH) resource, and a synchronization signal (SS) block resource.

More characteristically, in the case of the RRM-RS, a fixed resource maybe used for neighboring cell measurement and a flexible resource may beused for serving cell measurement. Transmission/reception points (TRPs)may exchange configurations of fixed resources with each other and mayconfigure the exchanged configurations for a UE.

The fixed resource may be configured with a longer period than theflexible resource and the period of the fixed resource may influence ondelay/accuracy of neighboring cell measurement. With respect to aneighboring cell with an excellent measurement result equal to orgreater than a threshold value, the UE may be configured to performmeasurement on the flexible resource of the neighboring cell. To performmeasurement in the flexible resource of the neighboring cell, the UE mayread a common PDCCH of the neighboring cell. For example, a serving cellmay signal information on a configuration of the common PDCCH of theneighboring cell and information on a transmission method such as aperiod to the UE or the neighboring cell may broadcast the correspondinginformation through an SIB or the like.

In addition, neighboring cell measuring report using the UE using theflexible resource may be triggered by a network. For example, flexibleresources may be additionally used only in aperiodic RRM reporttriggered by the network.

<Summary of Slot Type Indication and Additional Proposals>

Additional proposals in addition to the above descriptions are describedbelow.

To design a group common PDCCH for slot type indication, potentialdifferences in NR compared to enhancements to LTE TDD for DL-ULinterference management and traffic adaptation (LTE eIMTA) need to beconsidered. For example, it may be required to consider that differentGP lengths are configured for respective UEs in NR. Such considerationmay be more important when different UEs use different numerologies orare related to different usage scenarios. In addition, it may berequired to consider indication of a slot structure in an NR networkthat provides multiple numerologies.

It may also be required to consider a relationship between a semi-staticconfiguration and dynamic slot type indication and, for example, thedynamic indication may override the semi-static configuration formeasurement for more flexible design of an NR system than LTE.

1. UE-Specific GP Configuration

In an unpaired spectrum in which UL and DL are used in a TDM manner, itmay be general to assume that a network operates in any one of UL and DLat one time irrespective of a used numerology.

In an LTE system, a cell-specific GP length may be configured for allUEs. However, it may be inefficient to configure the same GP length forall UEs in a cell in the NR system. For example, when a GP length isconfigured as 2 symbols based on numerology corresponding to SCS of 15kHz, the corresponding GP length may correspond to 8 symbols innumerology corresponding to SCS of 60 kHz. As such, the GP lengthcorresponding to 8 symbols may be a longer time period than a GP lengththat is actually required for a UE that operates based on SCS of 60 kHzand a radio resource may be wasted.

In consideration different propagation delays, different numerologies,and/or different QoS requirements, a UE-specific GP configuration may bemore appropriate than a cell-specific/UE-common GP configuration in NR.To use a UE-specific GP, a maximum GP supported by a network may besignaled to a UE. In addition, the UE-specific GP may be determined andsignaled.

As such, NR may support a UE-specific GP configuration.

2. UE Operation According to Slot Type

When slot type indication is given, a UE may determine a DL symbol, a ULsymbol, and/or other symbols (e.g., flexible symbols) from the slot typeindication. Detailed contents on the slot type indication may indicate,for example, one of predefined slot patterns, bitmap of DL/UL, and/orlengths of DwPTS and UpPTS but are not limited thereto. To indicate aproper slot type, it may be required to define handling of different GPlengths.

In signaling of a DL portion (resource) and a UL portion (resource) fora group common PDCCH, two approaches may be broadly considered.

(i) A first method is to indicate the base case for the DL/UL portionsby a network. For example, the DL/UL portions may be indicated accordingto the minimum GP that is supported by the network. In this case, a UEwith a larger GP length than the minimum GP may determine where anadditional required GP is positioned, based on the indicated slotstructure.

(ii) A second method is to indicate the worst case for the DL/ULportions by a network. For example, the DL/UL portions may be indicatedaccording to the maximum GP supported by the network. In this case,separate mechanisms for using other resources (e.g., flexible) indicatedby slot indication may be used for DL or UL for a UE with a smaller GPthan the maximum GP.

In addition, it may be required to determine where a GP indicated by aslot type is positioned with respect to UEs with different GP lengths.

For example, a UE may assume that a GP is always ended after the DLportion. When slot 1 is dedicated for DL and slot 2 positioned afterslot 1 is dedicated for UL, the GP may be positioned at the beginning ofslot 2 dedicated for UL. When the minimum GP is indicated according toslot type indication, a UE with a larger GP than the minimum GP mayreduce the UL portion to ensure an additional GP.

As another example, a UE may assume that a GP is always positionedbefore starting of the UL portion. When slot 1 is dedicated for DL andslot 2 is dedicated for UL, the GP may be positioned in a DL slot. Whenthe minimum GP is indicated by slot type indication, a UE with a largerGP than the minimum GP may reduce the DL portion to ensure an additionalGP.

Alternatively, a GP may be generated by dynamic scheduling only. Forexample, a UE may create a GP between ending of DL reception (e.g.,ending of a control channel, ending of DL data, or ending ofmeasurement) and starting of UL transmission. However, this method maycomplicate an operation of the UE. Accordingly, it may be more desirableto determine to insert a GP into ending of DL or starting of UL.

Based on the above discussion, it may be required to determine whether aslot structure indicated by a common PDCCH is formed assuming the bestGP case or the worst GP case, which is supported by a network. Inaddition, the GP may be positioned after the DL portion or before the ULportion.

3. Handling of Different Numerologies and Different Slot Sizes

A slot size may be related to the numerology. When numerology of DL orUL is changed, an actual effect may be changed depending on arelationship between numerology used in slot type indication andnumerology used in control/data transmission. The common PDCCH mayindicate a slot type and numerology used as reference for slot typeindication may be important to a UE.

For example, slot type indication may be transmitted base on thereference numerology. Based on the reference numerology, the UE mayinterpret the indicated slot type as numerology of the UE and mayestimate a proper size of a slot irrespective of numerology used in theUE.

As another example, a common PDCCH may indicate a slot type usingnumerology of a UE. In this case, the UE may not need to re-estimate aslot type and a slot size. In this case, the common PDCCH may need to beUE-separately transmitted according to numerology.

However, as described above, a network may operate in one direction(e.g., DL/UL) at one time irrespective used numerology. Accordingly, itmay be advantageous to transmit slot type indication based on thereference numerology. For example, when a network operates based onnumerology with SCS of 15 kHz and 60 kHz and transmits slot typeindication based on SCS of 15 kHz, a UE using SCS of 60 kHz mayinterpret a different number of DL portions (e.g., DL symbols) and ULportions (e.g., UL symbol) from indication based on symbol levelalignment or slot level alignment.

As a detailed example, FIG. 2 illustrates 1 slot based on SCS of 15 kHzand 1 slot based on SCS of 60 kHz. That is, 1 symbol duration (i.e.,time duration) based on SCS of 15 kHz may be the same as 4 symboldurations based on SCS of 60 kHz. Assuming that slot format indicationbased on SCS of 15 kHz indicates a slot forma having [Symbol 0=DL,Symbol 2=DL . . . , Symbol 13=UL], a UE that operates based on SCS of 60kHz may interpret Symbol 0=DL as 4 consecutive DL symbols, may interpretSymbol 2=DL as 4 consecutive DL symbols, and may interpret Symbol 13=ULas 4 consecutive UL symbols (e.g., symbol level alignment). According toslot level alignment, a slot having an indicated format may beinterpreted to be repeated four times.

Such SCS of 15 kHz and 60 kHz is exemplary and the same method may beapplied to various SCSs that have been aforementioned with reference toTable 1 above. For example, when SCS 1 is A kHz, SCS 2 is B kHz, and arelationship of B=A*M is satisfied (where A, B, and M being a naturalnumber), 1 OFDM symbol length based on SCS 1 may be the same as M OFDMsymbol lengths based on SCS 2.

A group common PDCCH may indicate a slot format based on the referencenumerology irrespective actual numerology used in a UE.

The reference numerology may be indicated by a network (e.g., RRCsignaling) or pre-configured. For example, the minimum SCS among variousSCSs configured for UEs by the network may be used as the referencenumerology.

4. UE Operation Related to Periodic Resource Configuration

In general, NR may be targeted to avoid always on signal or periodictransmissions, some periodic configurations may be required for someoperations. For example, a synchronization signal (SS) block, a PRACHconfiguration, a CSI-RS configuration, an RRM-RS configuration, and/orgrant-free resources may be periodically configured.

In terms of UE performance, it may be desirable to ensuresemi-statically configured resources. However, in terms of flexibility,dynamic resource switching between DL/UL/Reserved may be limited. Inconsideration of such advantages and disadvantages, the two followingapproaches may be considered.

(i) For example, when a semi-static configuration is provided, a UE mayassume that resources are used according to a correspondingconfiguration. For example, a group common PDCCH may be defined not tochange a type of a resource configured by a semi-static configuration.This method may be advantageous to enhance UE performance and tosimplify a fallback operation.

(ii) As another example, a resource indicated by a semi-staticconfiguration may be considered as a potential candidate of asemi-static resource. When a group common PDCCH is not activated, apotential candidate may be assumed to be ensured. When the group commonPDCCH is activated, the semi-static resource may be used only when beingchecked by the group common PDCCH. According to this method, it may beadvantageous to enhance network flexibility. However, even if a slottype is not changed in a fallback configuration that is semi-staticallyconfigured, it may be required to transmit the group common PDCCH and,thus, signaling overhead may be increased.

In consideration of advantage/disadvantage of (i) and (ii), thesemi-static resource may distinguish between a first group and a secondgroup, the first group may comply with operation (i), and the secondgroup may comply with the operation (ii). Minimum UE performance onmeasurement and minimum opportunities for a PRACH may be ensured throughthe first group and the second group may be used in an on-demand manner.

A common PDCCH may override at least a portion of a semi-staticallyconfigured resource. Semi-static configurations having differentpriority from the common PDCCH, for example, a guaranteed resource and aflexible resource may be considered.

<Slot Format Indicator (SFI) for Different Numerology>

As described above, a slot format indicated through a group common PDCCHmay include downlink (D), unknown (X), and/or uplink (U) symbols.

A plurality of slot formats may configure various combinations and acombination(s) of slot formats may be configured for a UE via higherlayer signaling or the like.

A plurality of numerologies may be configured for a UE. An SFI of thegroup common PDCCH may indicate an index of a slot format table (or slotformat combinations/sets) configured or the UE. When a plurality of BWPsand a plurality of numerologies are configured for 1 UE, there may be amethod of indicating slot formats for respective numerologies. Forexample, numerologies may be separately configured for respective BWPsand, in this case, slot formats may be indicated for the respectiveBWPs.

1. UE Slot Format Table for Multi-Numerology

(1) Single Column Table

A slot format table configured for a UE may be a set of slot formats ofa plurality of numerologies.

For example, when SCS configured for a UE is 15 and 30 kHz and the slotformat table configured for the UE includes 16 of total entries, entries#1 to #8 may correspond to slot formats of SCS of 15 kHz and entries #9to #16 may correspond to slot formats of SCS of 30 kHz. An SFI of agroup common PDCCH may indicate a slot format index appropriate fornumerology used by the UE.

When a plurality of BWPs is activated in a UE and the respective BWPshave different numerologies, slot formats of the plurality of BWPs maybe indicated through one SFI. For example, index offset between slotformats to be applied to numerologies may be used to indicate slotformats of a plurality of BWPs through 1 SFI.

Like in the above example, it may be assumed that, when SCS configuredfor a UE is 15 and 30 kHz and the slot format table configured for theUE includes 16 of total entries, entries #1 to #8 correspond to slotformats of SCS of 15 kHz and entries #9 to #16 correspond to slotformats of SCS of 30 kHz. In this case, when an SFI indicates one indexof #1 to #8, a UE may acquire a slot format without change using anindex of the SFI in a BWP of SCS of 15 kHz but may interpret an index ofSFI+8 in a BWP of SCS of 30 kHz (i.e., index offset 8 is applied) toacquire a slot format of a BWP of SCS of 30 kHz.

(2) Multiple Column Table

A mother table that is a reference of a slot format table configured fora UE or a slot format table configured for the UE may correspond to aset of slot formats of a plurality of numerologies.

For example, as shown in Table 4, columns may be defined for respectivenumerologies and columns may define slot formats appropriate for thecorresponding numerologies.

TABLE 4 15 kHz 30 kHz 60 kHz 120 kHz SCS SCS SCS SCS . . . Slot format 1. . . . . . . . . . . . . . . Slot format 2 . . . . . . . . . . . . . .. . . . Slot format N . . . . . . . . . . . . . . .

When a plurality of BWPs is activated in a UE and the respective BWPshave different numerologies, even if one SFI is indicated, a UE mayrecognize slot formats of respective numerologies in a row correspondingto the SFI.

2. Automatic Slot Format Expansion/Reduction

As another example of the present invention, a UE slot format table ofone numerology (e.g., reference numerology) may be defined and a rulemay be defined to expand or reduce the corresponding table according tonumerology. In this case, it may not be required tonumerology-separately indicate a slot format by a network and, thus,signaling overhead may be advantageously reduced.

(1) Expansion Rule

When a UE uses larger SCS than reference SCS as a reference of the UEslot format table, the number of UE SCS-based slots may be increasedcompared with the number of reference SCS-based slots included for thesame time duration. For example, 4 slots based on reference SCS of 15kHz may have the same time duration as 8 slots based on SCS of 30 kHz.Accordingly, the UE needs to expand a slot format indicated based on thereference SCS according to SCS used by the UE. Here, expansion of a slotformat refers to expansion of the number of symbols included in a slotbut does not refer to expansion of absolute time duration. For example,when the network indicates time direction of 0.5 ms including 14symbols, the UE may be interpreted to be expanded to include 28/56/ . .. symbols in the same time duration of 0.5 ms.

-   -   Option 1: Downlink (D), unknown (X), and uplink (U) directions        of symbols of respective slot formats indicated by the reference        SCS may be maintained contains for time duration occupied by the        corresponding slot format. For example, it may be assumed that        the reference SCS is 15 kHz and a slot format indicated by the        reference SCS includes 4 D symbols, 6 X symbols, and 4 U symbols        and SCS used by the UE is 30 kHz. In this case, the 4 D symbols,        the 6 X symbols, and the 4 U symbols, included in the indicated        slot format, may be expanded to 8 D symbols, 12 X symbols, and 8        U symbols, respectively, with respect to a UE that operates        based on SCS of 30 kHz. That is, time duration of 4 D symbols        based on SCS of 15 kHz is the same as time duration of 8 D        symbols based on SCS of 30 kHz and, thus, the UE may interpret 4        D symbols indicated based on SCS of 15 kHz to 8 D symbols based        on SCS of 30 kHz. In this case, the number of D symbols may be        expanded but the sum of time durations of D symbols in a slot        may be maintained contain. The UE may interpret X symbols and U        symbols in the same manner.    -   Option 2-1: When a UE expands each D symbol and each U symbol,        different rules may be applied according to whether an X symbol        is present before and after a corresponding symbol. For example,        when a D symbol, a rear portion of which is an X symbol, is        expanded as the case in which SCS used by the UE is equal to or        greater than twice the reference SCS, the UE may configure ½ of        a rear portion of the expanded D symbol as X. When a U symbol, a        front portion of which is an X symbol, is expanded, the UE may        configure ½ of a front portion of the expanded U symbol as X.        For example, when the reference SCS is 15 kHz and the number of        D symbols, X symbols, and U symbols is 4, 6, and 4,        respectively, 4 D symbols may be expanded to 4 D symbols+4 X        symbols based on SCS of 30 kHz. 6 indicated X symbols may be        expanded to 12 X symbols. 4 indicated U symbols may be expanded        to 4 X symbols+4 U symbols based on SCS of 30 kHz. As a result,        a slot format may be interpreted as 4 D symbols+20 X symbols+4 U        symbols. Accordingly, time duration corresponding to an X symbol        may be further increased compared with the indicated slot        format.    -   Option 2-2: When SCS used by a UE is equal to or greater than 4        times the reference SCS and a D symbol, a rear portion of which        is an X symbol, is expanded, a UE may configure ¼ of a rear        portion of the expanded D symbol as an X symbol. When a U        symbol, a front portion of which is an X symbol, is expanded, ¼        of a front portion of the expanded U symbol may be configured as        an X symbol.    -   Option 2-3: When SCS used by a UE is equal to or greater than 8        times the reference SCS and a D symbol, a rear portion of which        is an X symbol, is expanded, a UE may configure ⅛ of a rear        portion of the expanded D symbol as an X symbol. When a U        symbol, a front portion of which is an X symbol, is expanded, ⅛        of a front portion of the expanded U symbol may be configured as        an X symbol.    -   Option 2-4: When SCS used by a UE is equal to or greater than 16        times the reference SCS and a D symbol, a rear portion of which        is an X symbol, is expanded, a UE may configure 1/16 of a rear        portion of the expanded D symbol as an X symbol. When a U        symbol, a front portion of which is an X symbol, is expanded,        1/16 of a front portion of the expanded U symbol may be        configured as an X symbol.    -   Option 3-1: When SCS used by a UE is equal to or greater than        twice the reference SCS and an X symbol is expanded, a format of        the expanded X symbol may also be differently determined        according to whether D/U symbols are present before and after        the X symbol. For example, when an X symbol, a front portion of        which is a D symbol, is expanded, the UE may configure ½ of a        front portion of the expanded X symbol as a D symbol. In        addition, when an X symbol, a rear portion of which is a U        symbol, is expanded, the UE may configure ½ of a rear portion of        the expanded X symbol as a U symbol.    -   Option 3-2: When SCS used by a UE is equal to or greater than 4        times the reference SCS and an X symbol is expanded, a format of        the expanded X symbol may also be differently determined        according to whether D/U symbols are present before and after        the X symbol. For example, when an X symbol, a front portion of        which is a D symbol, is expanded, the UE may configure ¼ of a        front portion of the expanded X symbol as a U symbol. In        addition, when an X symbol, a rear portion of which is a U        symbol, is expanded, the UE may configure ¼ of a rear portion of        the expanded X symbol as a U symbol.    -   Option 3-3: When SCS used by a UE is equal to or greater than 8        times the reference SCS and an X symbol is expanded, a format of        the expanded X symbol may also be differently determined        according to whether D/U symbols are present before and after        the X symbol. For example, when an X symbol, a front portion of        which is a D symbol, is expanded, the UE may configure ⅛ of a        front portion of the expanded X symbol as a U symbol. In        addition, when an X symbol, a rear portion of which is a U        symbol, is expanded, the UE may configure ⅛ of a rear portion of        the expanded X symbol as a U symbol.    -   Option 3-4: When SCS used by a UE is equal to or greater than 16        times the reference SCS and an X symbol is expanded, a format of        the expanded X symbol may also be differently determined        according to whether D/U symbols are present before and after        the X symbol. For example, when an X symbol, a front portion of        which is a D symbol, is expanded, the UE may configure 1/16 of a        front portion of the expanded X symbol as a U symbol. In        addition, when an X symbol, a rear portion of which is a U        symbol, is expanded, the UE may configure 1/16 of a rear portion        of the expanded X symbol as a U symbol.

(2) Reduction Rule

When a UE uses smaller SCS than reference SCS, a smaller number ofslots/symbols than the number indicated based on the reference SCS maybe present for the same time duration. For example, 8 slots based onreference SCS of 30 kHz may have the same the same time duration as 4slots based on SCS of 15 kHz. Accordingly, the UE needs to expand a slotformat indicated based on the reference SCS according to SCS used by theUE.

-   -   Option 1-1: When SCS (hereinafter, UE SCS) used by a UE is        smaller than the reference SCS and even one of D or U is present        in a symbol set of the reference SCS to be reduced to 1 symbol        of the UE SCS, the corresponding symbol set may be interpreted        as one D symbol or U symbol based on the UE SCS.    -   Option 1-2: When the UE SCS is small and is equal to or less        than ½ times the reference SCS and a portion of D or U in a        symbol set of the reference SCS to be reduced to 1 UE SCS symbol        is equal to or greater than ½, the corresponding symbol set may        be configured to be a D or U symbol of the UE SCS. When the        portion of D or U is less than ½, the corresponding symbol set        may be configured to be an X symbol of the UE SCS. For example,        when a slot format DDDXXXXXXXXUUU based on reference SCS of 30        kHz is indicated, 2 symbols such as |DD|DX|XX|XX|XX|XU|UU| may        be grouped to define 1 symbol of UE SCS of 15 kHz. |DX| may be        converted into D and |XU| may be converted into U. A slot format        DDDXXXXXXXXUUU based on SCS of 30 kHz may be converted into a        slot format DDXXXUU based on UE SCS of 15 kHz.    -   Option 1-3: When the UE SCS is small and is equal to or less        than ¼ times the reference SCS and a portion of D or U in a        symbol set of the reference SCS to be reduced to 1 UE SCS symbol        is equal to or greater than ¾, the corresponding symbol set may        be configured to be a D or U symbol of the UE SCS. When the        portion of D or U is less than ¾, the corresponding symbol set        may be configured to be an X symbol of the UE SCS.    -   Option 1-4: When the UE SCS is small and is equal to or less        than ⅛ times the reference SCS and a portion of D or U in a        symbol set of the reference SCS to be reduced to 1 UE SCS symbol        is equal to or greater than ⅞, the corresponding symbol set may        be configured to be a D or U symbol of the UE SCS. When the        portion of D or U is less than ⅞, the corresponding symbol set        may be configured to be an X symbol of the UE SCS.    -   Option 1-5: When the UE SCS is small and is equal to or less        than 1/16 times the reference SCS and a portion of D or U in a        symbol set of the reference SCS to be reduced to 1 UE SCS symbol        is equal to or greater than 15/16, the corresponding symbol set        may be configured to be a D or U symbol of the UE SCS. When the        portion of D or U is less than 15/16, the corresponding symbol        set may be configured to be an X symbol of the UE SCS.    -   Option 2-1: When the UE SCS is smaller than the reference SCS        and even one X is present in a symbol set of the reference SCS        to be reduced to 1 symbol of the UE SCS, the corresponding        symbol set may be converted into an X symbol of the UE SCS.    -   Option 2-2: When the UE SCS is small and is equal to or less        than ½ times the reference SCS, a symbol set of the reference        SCS to be reduced to 1 symbol of the UE SCS includes D and X or        X and U, and a portion of X in the symbol set is equal to or        greater than ½, the corresponding symbol set may be configured        to be an X symbol of the UE SCS. When the portion of X in the        symbol set is less than ½, the corresponding symbol set may be        configured to be a D or U symbol of the UE SCS.    -   Option 2-3: When the UE SCS is small and is equal to or less        than ¼ times the reference SCS, a symbol set of the reference        SCS to be reduced to 1 symbol of the UE SCS includes D and X or        X and U, and a portion of X in the symbol set is equal to or        greater than ¾, the corresponding symbol set may be configured        to be an X symbol of the UE SCS. When the portion of X in the        symbol set is less than ¾, the corresponding symbol set may be        configured to be a D or U symbol of the UE SCS.    -   Option 2-4: When the UE SCS is small and is equal to or less        than ⅛ times the reference SCS, a symbol set of the reference        SCS to be reduced to 1 symbol of the UE SCS includes D and X or        X and U, and a portion of X in the symbol set is equal to or        greater than ⅞, the corresponding symbol set may be configured        to be an X symbol of the UE SCS. When the portion of X in the        symbol set is less than ⅞, the corresponding symbol set may be        configured to be a D or U symbol of the UE SCS.    -   Option 2-5: When the UE SCS is small and is equal to or less        than 1/16 times the reference SCS, a symbol set of the reference        SCS to be reduced to 1 symbol of the UE SCS includes D and X or        X and U, and a portion of X in the symbol set is equal to or        greater than 15/16, the corresponding symbol set may be        configured to be an X symbol of the UE SCS. When the portion of        X in the symbol set is less than 15/16, the corresponding symbol        set may be configured to be a D or U symbol of the UE SCS.    -   Option 3: When the UE SCS is smaller than the reference SCS and        a symbol set of the reference SCS to be reduced to 1 SCS symbol        includes all of D, X, and U, the corresponding symbol set may be        configured to be an X symbol of the UE SCS.    -   Option 4-1: When the UE SCS is smaller than the reference SCS        and D and U are mixed in a symbol set of the reference SCS to be        reduced to 1 SCS symbol, the corresponding symbol set may be        configured as an X symbol of the UE SCS.    -   Option 4-2: When the UE SCS is smaller than the reference SCS        and D and U are mixed in a symbol set of the reference SCS to be        reduced to 1 SCS symbol, the UE may recognize the corresponding        symbol set as an error and may disregard a slot format of a slot        included in the corresponding symbol set.

(3) Default of Reference Numerology

There may be various methods of notifying a UE about referencenumerology to configure reference numerology by a network.

-   -   Option 1: For example, when notifying a UE about a slot format        table (e.g., combinations of slot formats), the network may also        notify the UE about reference numerology referred to by the slot        format table.

However, when default reference numerology is defined and a slot formattable based on default reference numerology is used, the network may notseparately notify the UE about reference numerology.

The default reference numerology may be defined, for example, as followsbut is not limited thereto. (i) Smallest numerology among numerologiesconfigurable for a UE may be selected as default reference numerology.For example, assuming that SCS of numerology configurable for the UE is15, 30, 60, and 120 kHz, the network may define 15 kHz as defaultreference numerology. (ii) Largest numerology among numerologiesconfigurable for a UE may be selected as default reference numerology.For example, assuming that SCS of numerology configurable for the UE is15, 30, 60, and 120 kHz, the network may define 120 kHz as defaultreference numerology. (iii) As another example, 15 kHz may be fixed todefault reference numerology.

-   -   Option 2: As another example, the network may define numerology        of a control channel used to indicate an index in a slot format        table configured for the UE as reference numerology.    -   Option 3: As another example, numerology of a band in which a        corresponding slot format is actually to be used may be defined        as reference numerology.

3. Inherits Earlier SFI

The method of converting a slot format depending on SCS of a UE by theUE when a slot format is transmitted based on the reference SCS (orreference numerology) has been described above.

When a carrier is changed after the UE applies a specific SFI andnumerology of the changed BWP/carrier is different from previousBWP/carrier, whether the specific SFI is re-applied by the UE may beissued according to the aforementioned slot format conversion rule.

-   -   Option 1: For example, when numerology of the changed        BWP/carrier is different a previous BWP/carrier, the UE may        disregard a pre-indicated slot format and may perform a fallback        operation up to a next SFI from a time point in which the        BWP/carrier is changed.    -   Option 2: As another example, when numerology of the changed        BWP/carrier is different a previous BWP/carrier, the UE may        apply a slot format that is modified according to the changed        numerology up to a next SFI from a time point in which the        BWP/carrier is changed. However, in the case of a format that is        not supported by the modified slot format, the UE may disregard        the corresponding slot format and may perform a fallback        operation.

4. Inherits Earlier SFI in Beam Switching

A plurality of beams may be configured for a UE and, as necessary, beamswitching may occur. As such, when a beam is switched, the UE may needto select whether an existing applied SFI is applied to a new beamwithout change.

-   -   Option 1: The UE may disregard an existing slot format up to a        next SFI from a time point in which beam switching occurs and        may perform a fallback operation.    -   Option 2: The UE may comply with an existing slot format up to a        next SFI from a time point in which beam switching occurs. When        numerology of the switched is different a previous beam, the UE        may apply a slot format modified according to the changed        numerology. However, in the case of a format that is not        supported by the modified slot format, the UE may disregard the        corresponding slot format and may perform a fallback operation.

5. Defining Reference Numerology

To perform a method of modifying a slot format according to numerologyas described above, it may be important to define reference numerology.When numerologies of scheduling/scheduled carriers are the same incross-carrier scheduling, there may be no problem to apply theaforementioned slot format modification rule. However, a plurality ofBWPs may be configured for respective carries and numerologies may bedifferent for the respective BWPs.

When an SFI is defined/signaled for each cell (i.e., carrier) in a groupcommon PDCCH transmitted through a PCell, it may be required to definereference numerology of a SFI for each cell.

For example, in the case of the PCell, numerology for transmitting thegroup common PDCCH may correspond to reference numerology.

In the case of a SCell, the following options may be considered.

-   -   Option 1: A slot format may be indicated based on numerology of        a currently activated BWP.    -   Option 2: Numerology of a first activated BWP in the SCell may        be defined as reference numerology of the SCell.    -   Option 3: Numerology of a default BWP of the SCell may be        defined as reference numerology of the SCell.

<Slot Format Indication for Multi-Band>

Slot format indication may be mainly used in a TDD environment but maybe used to indicate a slot format in an FDD band. Each band of the FDDmay be generally fixed to D or U but a network may permit each band ofthe FDD to be used for other use through ‘Unknown’. In this case, thenetwork needs to indicate a slot format of D Band and U Band in a FDDand, thus, there is a need for a method therefor.

In an LTE-NR coexistence environment, a network may allocatesupplementary uplink (SUL) that temporally use an LTE UL band to an NRuser for an additional UL band of an NR user. In this case, when the NRuser operates in a TDD, the network needs to simultaneously indicate aslot format of an NR TDD band and a slot format of SUL.

Such a method of simultaneously indicating a slot format for two or morebands is described below.

1. Single Column Table

For example, a table in which slot formats of two or more bands (e.g.,BWPs) are contiguously deployed in one line may be defined/configured.

FIG. 3 illustrates combinations of slot formats according to anembodiment of the present invention.

For example, when a slot format of Band1 is represented as SF1 and aslot format of Band2 is represented as SF2, a slot format grouptransmitted to a UE by a network may has the form of SF1+SF2+ . . . .The slot format group may be one entry in the slot format table and suchentries may be grouped to configure the slot format table.

The network may configure combination(s) of slot formats correspondingto the slot format table for the UE via higher layer signaling and,then, may notify the UE about a slot format combination of a specificentry through a group common PDCCH.

In addition, SCS may be different for each band even in one entry.Accordingly, the numbers of slots of respective SFs may also bedifferent.

The slot format table may be configured in such a way that slotscorresponding to the same specific time duration are contiguouslydeployed among slot formats of respective bands and, then, slotscorresponding to next the same time duration are contiguously deployed.

For example, it may be assumed that numerology of Band 1 is SCS of 60kHz and numerology of Band 2 is SCS of 15 kHz. Band 1 may have 4 slotsand Band 2 may have 1 slot for 1 ms. When time duration of a slot formatto be notified to a UE by a network is 2 ms, the number of slots ofBand1 is 8 for 2 ms and the number of slots of Band2 is 2 for 2 ms. Inthis case, the network may deploy slots formats of 2 bands in the formof 1 slot of 4 slots of Band1+1 slot of Band2+4 slots of Band1+1 slot ofBand2.

For example, the network may deploy 1 slot of 4 slots+1 slot of Band2,which corresponds to the same time duration of 1 ms, and, then, maydeploy 4 slots of Band1+1 slot of Band2, which correspond to next timeduration of 1 ms.

Such slot format deployment may be performed irrespective of the numberof bands.

FIG. 4 illustrates combinations of slot formats according to anotherembodiment of the present invention. For convenience, it may be assumedthat the number of bands is 2 or 3 in FIG. 4. For example, in the caseof entry 2, Band 1, Band 2, and Band 3 have the same SCS. In the case ofentry 4, it may be assumed that SCS of Band 2 is twice SCS of Band 1 andSCS of Band 1 is twice SCS of Band 3.

The method of FIG. 3 or 4 may be used when a network indicates slotscorresponding to the same time duration with respect to a plurality ofbands at one time.

2. Multi-Column Table

FIGS. 5 and 6 illustrate combinations of slot formats according toanother embodiment of the present invention.

Slot formats of a plurality of bands may be contiguously deployed in onecolumn as illustrated in FIG. 3 or 4 but, according to anotherembodiment of the present invention, a column may be defined for eachband and a slot format may be indicated.

3. Multi-Bands Supporting Multi-Numerology

The method of indicating a slot form of all numerologies to be supportedby one band through one slot format table has been described above withregard to embodiments related to Table 4 above. The method of indicatingslot formats of a plurality of bands through one slot format table hasbeen described with regard to the embodiments related to FIGS. 3 to 6.

The above embodiments may also be combined to consider a method ofsimultaneously indicating slot formats of all numerologies to besupported for each of the plurality of bands. For example, an embodimentmay be formed by combining the embodiments related to Table 4 above andthe embodiments related to FIGS. 3 to 6.

For example, a column may be defined for each band and a sub-column maybe defined for numerologies of respective bands and, thus, a network mayindicate slot formats for respective numerologies of a plurality ofbands in one row at one time.

FIG. 7 illustrates a combination of slot formats according to anembodiment of the present invention.

In FIG. 7, the number of bands and the number of numerologies of therespective bands may be changed as one example. As the number of bandsand/or the number of numerologies of the respective bands are increased,a size of the illustrated slot format table may also be increased.

4. Reference Numerology Setting

When slot formats of a plurality of bands are indicates using one table,numerology of each band needs to be considered. This is because a methodof indicating slot formats of respective bands is changed according todetermined reference numerology. Each band may be any one of, forexample, a DL band, a UL band, a SUL band, and a TDD band but is notlimited thereto.

Considered methods are described below.

-   -   Option 1: A slot format indicated by a slot format table may be        a slot format according to numerology of each band. For example,        when Band1 is SCS of 30 kHz and Band2 is SCS of 15 kHz, a slot        format of each band may be defined as a slot format for SCS of        30 kHz and a slot format for SCS of 15 kHz. When slot formats        for SCS of 30 kHz/SCS of 15 kHz are inserted into a table, a        combination of slot formats of SCS of 30 kHz/SCE of 15 kHz or a        slot format column for each band may be deployed.    -   Option 2: A slot format may be indicated based on smallest        numerology among numerologies of a plurality of bands. A UE may        modify a slot format indicated according to numerology of each        band using the aforementioned slot format expansion method.    -   Option 3: A slot format may be indicated based on largest        numerology among numerologies configured for a plurality of        band.    -   Option 4-1: Reference numerology may be separately defined and a        slot format of each band may be indicated based on the reference        numerology.    -   Option 4-2: Reference numerology may be separately defined and        slot formats of only some bands may be indicated based on the        reference numerology. A slot format according to numerology of a        corresponding band may be indicated for the other band(s). For        example, some bands to which the reference numerology is applied        may be at least one of a DL band, a UL band, a SUL band, and a        TDD band.

Reference numerology in Options 4-1 and 4-2 may be determined using theaforementioned method of determining reference numerology.

While the proposed methods may be implemented independently, someproposed methods may be combined (or integrated). It may be regulatedthat information indicating whether the proposed methods are applied ornot (or information about rules of the proposed methods) is transmittedto a UE in a predefined signal (e.g., a physical-layer signal or ahigher-layer signal) by a base station.

<Group Common PDCCH>

Hereinafter, the content and expected payload size of DCI transmittedthrough a group common PDCCH are described.

A signaling method of the group common PDCCH is described now. Anexample of the signaling method may include a method of allocating andtransmitting a reserved resource and a method of configuring andtransmitting a search space.

When information on a slot type is transmitted through the group commonPDCCH, whether a method of transmitting a slot type to a UE thatoperates with a plurality of CCs is effective is described below.

1. Contents of Group Common PDCCH

(1) Slot Format Indication

The group common PDCCH may be used to notify a UE about a slot format.The slot format may be indicated in various types. A payload size of thegroup common PDCCH may be variable according to a type of an indicatedslot format.

A size of 1 slot (e.g., length in the time domain) may be changedaccording to numerology. The number of slots configuring 1 slot may bechanged according to numerology.

(i) Slot Type

The group common PDCCH may indicate a type of at least one slot.

For example, a slot may be classified as shown in Table 5 below but isnot limited thereto.

TABLE 5 Slot Description D only Slot in which only downlink is supportedU only Slot in which only uplink is supported D-centric Slot in whichdownlink is supported in most symbols configuring slot U-centric Slot inwhich uplink is supported in most symbols configuring slot Data regionSlot used for other data but not UE specific data like (DR) in MBSFNsubframe Reserved Slot occupied by a network as necessary but not UEspecific use

In the case of D-centric and U-centric slot types, only whether acorresponding slot is D-centric or U-centric may be indicated and, thus,a configuration (e.g., downlink and uplink) of an actual symbol includedin the corresponding slot needs to be predefined. A DL/UL portion in aD/U-centric slot may be predefined or may be configured by a network.One or more D/U-centric patterns may be present according to a DL/ULresource configuration.

Use of the reserved/DR slot may be predefined or not. For example, theuse of the reserved/DR slot may be predefined via system information,higher layer indication, or the like. When the use of a reserved/DR slotis not defined, a network may simultaneously notify a UE about the usewhile indicating a slot type through the group common PDCCH or may notindicate the use if it is not required for the UE to know the use of thereserved/DR slot. The reserved resource may be separately configuredfrom a slot type. For example, the network may configure a reservedresource via dynamic/semi-static signaling.

(ii) Slot Type Pattern

A group common PDCCH may indicate a type of a plurality of slots. Forexample, the group common PDCCH may indicate at least one ofcombinations of a plurality of slots. When a network indicatesrespective types of a plurality of slots one by one, it may beineffective that a payload size of the group common PDCCH is increasedand signaling overhead is increased. Accordingly, the number of slots tobe indicated and each slot type may be defined as one pattern, and thenetwork may notify the UE about an index of the pattern through thegroup common PDCCH.

A plurality of slot type patterns may be defined. For example, the slottype pattern may be defined as [periodicity/slot types or patterns or aset of slot types] but is not limited thereto.

FIG. 8 illustrates patterns of slot formats according to an embodimentof the present invention. In FIG. 8, DU refers to a symbol, a half ofwhich is D symbols and the other half of which is U symbols.

In the case of an FDD system, a slot corresponding to D in FIG. 8 maycorrespond to a slot format of a DL band (e.g., DL BWP) and a slotcorresponding to U in FIG. 8 may be interpreted as a slot format of a ULband (e.g., UL BWP). For example, a configuration of a pattern obtainedby combining a D slot format and a U slot format for a UE by a basestation may be interpreted as a configuration of a pattern obtained bycombining a slot format of a DL band (e.g., DL BWP) and a slot format ofa UL band (e.g., UL BWP) for the UE by the base station.

A plurality of slot type patterns to be used in a corresponding cell ora corresponding group may be defined/configured and a network may notifya UE about patterns to be used among a plurality of slot type patterns.For example, a subset may be signaled to the UE among defined patterns.FIG. 8 illustrates 12 of total patterns and, in this case, informationindicating that patterns #5 to #8 defined using 2 slot sections among 12patterns are available may be signaled to the UE. In this case, 4patterns #5 to #8 may be re-indexed and may be considered as patterns #1to #4.

As such, when a subset of slot type patterns is pre-notified to the UE,the network may sequentially transmit only the indexes of the re-indexedpatterns to the group common PDCCH. Accordingly, signaling overhead ofthe group common PDCCH may be reduced. For example, the group commonPDCCH may not inevitably cover all 12 patterns and may be configured tocover 4 patterns and, in this case, a payload size of the group commonPDCCH may be reduced.

Information on the subset of the slot type patterns may be transmittedto the UE through a MAC control element (CE) or may be transmittedthrough the group common PDCCH. Alternatively, the network may predefinea period in which a pattern is to be indicated through systeminformation. Alternatively, information on a subset of slot typepatterns may be transmitted via UE-specific higher layer signaling.

A pattern of a long period may be defined in the form in which patternsof short periods are repeated. In this case, in a situation in which thenetwork needs to simultaneously indicate two slot formats, patterninformation on the long period may be advantageously replaced withpattern information on the short period.

(iii) Symbol Unit Indication

According to another embodiment of the present invention, a group commonPDCCH may indicate a slot type in units of symbols configuring a slot.For example, a resource type such as D/U/Reserved in Table 6 below maybe applied in units of symbols.

Table 6 below shows an exemplary slot format under the assumption that 1slot includes 7 symbols.

TABLE 6 Slot Format Symbol 0 Symbol 1 Symbol 2 Symbol 3 Symbol 4 Symbol5 Symbol 6 1 D D D D U U U 2 D D R R R R U 3 D U U U U U U 4 D D DR DRDR DR DR . . .

(iv) Symbol Pattern

Although the method of indicating an index of a slot pattern by a groupcommon PDCCH has been described above, the group common PDCCH mayindicate an index of a symbol pattern according to another embodiment ofthe present invention.

[Table 7]

Table 7 below shows an exemplary symbol pattern (or slot format) underthe assumption 1 slot includes 7 symbols.

TABLE 7 Symbol Pattern Symbol 0 Symbol 1 Symbol 2 Symbol 3 Symbol 4Symbol 5 Symbol 6 1 D D D R R U U 2 D DR DR DR U U U 3 R R R R R U U . ..

(2) Other Information

The group common PDCCH may further include other information in additionto slot format information.

(i) Puncturing Indication: The group common PDCCH may include puncturinginformation for URLLC. A period used as the URLLC may be indicated inunits of slots or in units of symbols.

(ii) Semi-Static Resource Information: The group common PDCCH mayinclude information on a semi-static resource such as CSI-RS. Forexample, the group common PDCCH may indicate information on what is acorresponding semi-static resource or information on a period,transmission time duration, and the like when the correspondingsemi-static resource has the period.

2. Transmission of Group Common PDCCH

As a method of transmitting a group common PDCCH by a network, a methodof configuring and transmitting a search space for the group commonPDCCH and a method of ensuring and transmitting a reserved resource forthe group common PDCCH may be considered.

(1) Transmission of Group Common PDCCH Using Reserved Resource

A network may pre-ensure a resource (e.g., RE, REG, RB, and CCE) inwhich a group common PDCCH is to be transmitted.

The group common PDCCH may also be a control channel and, thus, may bedeployed on a CORESET. In addition, it may be desirable to deploy aposition of the reserved resource for the group common PDCCH to minimizeblocking with other control channels. In particular, the group commonPDCCH may avoid blocking with a CSS to a maximum degree.

When a position in a logical domain, in which a control channel istransmitted, is defined, a logical position of the reserved resource forthe group common PDCCH may be immediately before or behind the CSS.Alternatively, the reserved resource for the group common PDCCH may bepositioned at the last portion of a CORESET or may be positioned to bespaced apart from a start index or end index of the CSS by predeterminedoffset. In this case, the offset may be different for each cell/group.The offset may be notified to a UE via system information, higher layersignaling, or the like.

Alternatively, the resource for the group common PDCCH may be deployedin the CSS. In this case, a size of the group common PDCCH may be equalto or less than a size of a smallest candidate among control channelcandidates in the CSS. In this case, the reserved resource for the groupcommon PDCCH may be included in the candidate of the CSS and, in thisregard, the UE may basically perform blind detection (DB) on the CSSirrespective of whether the group common PDCCH is detected in thereserved resource in the CSS.

A position of the reserved resource for the group common PDCCH may benotified to the UE via system information, higher layer signaling, orthe like. When the group common PDCCH is transmitted through a candidateon the CSS, the number of available candidates may be reduced totransmit PDCCH (e.g., common control information but not a group commonPDCCH) in the CSS, which causes a similar result to CSS blocking.Accordingly, when the group common PDCCH is configured in a CSS, the UEmay assume that a candidate, to which the group common PDCCH is mapped,is not used as a CSS candidate of another channel and may assume thecandidate to be an invalid candidate. The UE may skip blind detection onthe invalid candidate and may proceed to a next candidate. In addition,the group common PDCCH may be defined to be transmitted using a CSS likea general PDCCH and, in this case, a general blind detection procedureon the CSS may also be performed on the group common PDCCH in the sameway.

FIG. 9 illustrates reserved resource allocation for a group common PDCCHaccording to an embodiment of the present invention. The group commonPDCCH may be mapped to a block indicated by dotted lines in FIG. 9.

(a) of FIG. 9 illustrates the case in which a reserved resource for thegroup common PDCCH is allocated to a first candidate. Accordingly, a UEmay omit blind detection of a general PDCCH with respect to thecorresponding block.

(b) of FIG. 9 illustrates the case in which a reserved resource for thegroup common PDCCH is allocated to a next portion of the last candidate.(c) of FIG. 9 illustrates the case in which a reserved resource for thegroup common PDCCH is allocated to a position with predetermined offsetfrom the last candidate.

(2) Transmission of Group Common PDCCH Through Search Space

A network may configure a search space in which a group common PDCCH isto be transmitted and a UE may perform blind detection in acorresponding search space to detect a group common PDCCH.

(i) With the G-RNTI

A search space in which a group common PDCCH is to be transmitted isreferred to as a GSS. A radio network temporary identifier (RNTI)required for detection of the group common PDCCH in the GSS is referredto as a G-RNTI. For example, a CRC of the group common PDCCH may bescrambled or masked through the G-RNTI.

1 UE may have one or plural G-RNTIs. For example, one UE may beconfigured with one or plural GSSs. The GSS may be defined irrespectiveof the number thereof.

a. GSS in CSS

For example, a network may randomly deploy in a CSS. To deploy the GSSin the CSS, the size and/or the number of candidates of the GSS may beequal to or less than the size and/or the number of candidates of theCSS. Candidates of the GSS may be contiguously deployed or may beseparately distributed and deployed.

When a size of a candidate of the GSS is the same as a size of acandidate of the CSS, a UE needs to additionally perform only CRSexamination on the GSS (e.g., CRC examination through R-RNTI) whileperforming blind detection on the CSS and, thus, a problem in terms ofoverhead of additional blind detection due to additional deployment ofthe GSS may be overcome.

FIG. 10 illustrates a GSS deployed in a CSS according to an embodimentof the present invention.

An environment in which a size of a largest candidate among GSScandidates is equal to or smaller than a size of the smallest candidateof a CSS and the number of GSS candidates is equal to or less than ahalf of the number of CSS candidates may be considered.

b. GSS in CORESET

Similarly to a USS, a network may randomly deploy GSSs across a CORESETaccording to a hashing function using a G-RNTI. Candidates of a GSS maybe contiguously deployed or may be separately distributed and deployed.

(ii) Without the G-RNTI

a. GSS in CSS

A network may deploy a GSS in a CSS. The present embodiment is partiallysimilar to the aforementioned method of deploying the GSS in the CSSbut, according to the present embodiment, the network may form the GSSand may deploy the GSS in the CSS to reduce the possibility of blockingwith a control channel to be transmitted in the CSS. The size/number ofGSSs may be equal to or less than the size/number of CSS candidates.

When there is no G-RNTI, a position of a candidate of a GSS needs to bedetermined. When a size of the candidate of the GSS is the same as asize of a candidate of the CSS, a UE a UE needs to additionally performonly CRS examination on the GSS while performing blind detection on theCSS and, thus, the number of additional blind detections due toadditional deployment of the GSS may be reduced.

A position of a GSS candidate to be deployed in each CSS candidate maybe defined via system information or higher layer signaling. Candidatesof the GSS may be contiguously deployed or may be separately distributedor deployed.

FIG. 11 illustrates GSS candidates having a fixed position in a CSSaccording to an embodiment of the present invention.

When a GSS candidate and a CSS candidate have the same size, a startindex of a CCE, corresponding to an even-numbered or odd-numberedcandidate of the CSS, may be used as a start index of a CCE of the GSScandidate.

When the number of CCEs of the GSS candidate is less than that of theCSS candidate, an index of an even-numbered or odd-numbered CCE in aneven-numbered or odd-numbered candidate of the CSS may be used as astart index of the CCE of the GSS candidate.

b. GSS in CORESET

When GSSs are contiguously configured without a separate RNTI like a CSSof LTE, a start index of a GSS may be given by applying offset to astart index or end index of a CSS.

The offset may be different for each cell/group. The offset may benotified to the UE via system information, higher layer signaling, orthe like.

When a group common PDCCH is transmitted to a portion of a CSS (when aGSS candidate is fixed or not), a UE may assume that the group commonPDCCH is transmitted only in a slot in which the CSS is transmitted or amini-slot.

When the group common PDCCH is transmitted to a CSS and a separateresource, an interval and resource of the slot in which the group commonPDCCH is to be transmitted or the mini-slot may be separately configuredfrom the CSS.

When a size of downlink control information (DCI) of the group commonPDCCH is different from DCI transmitted in the CSS, a set of slots to bemonitored for the group common PDCCH by a UE may be different from a CSSmonitoring set. More generally, a slot monitored by the UE or amini-slot set may be differently configured for each RNTI or a slotmonitored by the UE or a mini-slot set may be differently configured foreach DCI size.

3. Slot Format Indication for Multiple Component Carriers

When a UE uses a plurality of carriers (e.g., carrier aggregation), anetwork may notify the UE about a slot format to be used in eachcarrier.

(1) Transmission of Group Common PDCCH of Multiple CC

A network may transmit a group common PDCCH for each CC to transmit slotformat indication for each CC. Alternatively, the network may indicateslot formats of all CCs through one primary CC (PCC).

When the number of CCs used by the UE is high, the network may group CCsto a plurality of groups and define a PCC for each group. The networkmay indicate a slot format of CCs in a corresponding group through a PCCof each group.

A method of grouping CCs is described below.

(i) CCs with the Same Slot Format

A network may group CCs with the same slot format to the same group. Inthis case, the network may indicate only a slot format of one CC withoutindicating a slot format for each CC. Accordingly, an amount ofinformation required for slot format indication and signaling overheadmay be reduced.

(ii) CCs with the Same Numerology

A network may group CCs with the same numerology to the same group. Inthis case, all CCs in a group may have the same slot length.Accordingly, the network may need to consider a difference in slotindexes due to a numerology difference when indicating slot formats withthe same time duration.

When a network transmits slot format information on a plurality of CCs,a payload size of a group common PDCCH may be significantly increased. Amaximum size of the payload of the group common PDCCH is [slot formatinformation of 1 CC*the number of CCs] and, thus, it may be difficult toincrease a size of slot format information of 1 CC. Slot formatinformation in units of symbols requires a large amount of informationand, thus, slot format indication to be used when a plurality of CCs isconfigured for the UE may be slot type indication or slot typeindication.

A payload size of a group common PDCCH for multiple CCs may bedetermined whether CCs are grouped. When the grouped CCs have the samenumerology, there is no problem in the case of the same indicated slottype but, when the respective CCs needs to receive indication ofdifferent slot types, it may be difficult to support a plurality of CCsby one slot format indication item.

When a slot format is indicated through a slot type pattern, a problemmay arise when periods of slot formats to be indicated by CCs in a groupare different. As a case in which lengths of slot formats to be receivedvia indication are different for respective CCs, when a UE receives aslot format of a long period, the slot format may be converted into aslot format of a short period. Alternatively, the network may performindication of a plurality of slot format periods through one slot formatindication item.

For example, a pattern of a long slot period may be defined through apattern in which a short slot period is repeated.

As another example, a pattern of a short slot period associated with apattern of a long slot period may be predefined. Even if a UE receives apattern of a long slot pattern, the UE may use a pattern of a short slotperiod matched with the corresponding pattern.

A more detailed example is described below with reference to FIGS. 12and 13. FIGS. 12 and 13 illustrate slot patterns of multiple CCsaccording to an embodiment of the present invention.

In FIGS. 12 and 13, it is assumed that CCs in a group include a CC thatreceives indication of 4 slots as a slot pattern period and a CC thatreceives indication of 2 slots as a slot pattern period.

Referring to FIG. 12, a pattern of 4 slot period may be defined in theform in which patterns of 2 slot periods are repeated twice.

Referring to FIG. 13, 2-slot period patterns associated with 4-slotperiod patterns may be defined.

When numerologies are different for respective CCs but the CCs have thesame time duration for slot pattern indication, a slot pattern periodmay be determined according to a difference in numerology. For example,a pattern of a short slot period may be used for a CC with short SCS anda pattern of a long slot period defined through the pattern of the shortslot period may be used for a CC for large SCS. This is because, in thecase of the same time duration, the number of slots of a CC with largeSCS is greater than the number of slots of a CC with small SCS.

FIG. 14 illustrates slot patterns of multiple CC according to anotherembodiment of the present invention. It may be assumed that a pattern of4 slots is a pattern of a CC using SCS of 30 kHz and a pattern of 2slots is a pattern of CC using SCS of 15 kHz.

In (a) of FIG. 14, a pattern of a 4-slot period may be defined in theform in which patterns of a 2-slot period are repeated twice.

In (b) of FIG. 14, a pattern of a 4-slot period and a pattern of a2-slot period may be associated with each other.

As such, slot patterns of a plurality of CCs using differentnumerologies may be indicated through one slot format indication.

When slot formats of a plurality of carriers are indicated through onegroup common PDCCH, a period of a slot format of each carrier may bematched based on a carrier in which the group common PDCCH istransmitted. When a period of a slot format of each carrier is shorterthan a reference period, a new configuration set according to repeatedpatterns/periods may be given. The case in which a period of a slotformat of a specific carrier is longer than a reference period may behandled in a similarly way.

(2) Slot Format Indication Methods

A CC index based on a network and a CC index based on a UE may bedifferent. Accordingly, a network may consider a CC index different whenindicating a slot format of a CC.

For example, when a CC based on a network is a NCC and a CC based on aUE is a UCC, NCC 1 may be classified into a plurality of UCCs (e.g., UCC1 to UCC n). When the network indicates a slot format based on the UCCas a reference of the UE, the UE may appropriately recognize indicatedinformation.

A relationship between the NCC and the UCC may be transmittedUE-specifically. For example, when the number of CCs configured as theNCC is m and the number of CCs configured as the UCC is n, arelationship between the NCC and the UCC may be defined by a network.The relationship between the NCC and the UCC may be signaled via a MACCE, system information, or a group common PDCCH.

Table 8 below shows an example of a relationship between a NCC and a UCCwith respect to one UE.

TABLE 8 NCC1 UCC1 UCC2 UCC3 NCC2 UCC4 UCC5 NCC3 UCC6 UCC7 UCC8 UCC9 . ..

(i) Slot Format Indication in Terms of Network

A network may indicate a slot format based on an index of an NCC. Uponreceiving indication of a slot format based on an index of the NCC, a UEmay find an index of a UCC of the UE, corresponding to the NCC, and mayuse the indicated slot format as a corresponding slot format of the UCCof the UE.

(ii) Slot Format Indication in Terms of UE

A network may indicate a slot format based on an index of a UCC. Thenetwork may define and indicate a slot format by as much as the numberUCC_max of UCCs of a UE that has a largest number of UCCs among UEsbelonging to the same group. The UE that has UCCs, the number of whichis less than UCC_max, may selectively acquire only indicationinformation by as much as the number of the UCCs of the UE and maydetermine a slot format for each UCC of the UE.

When mapping between the NCC and the UCC is performed in a similar waywith respect to a plurality of UEs, it may be easy to indicate a slotformat based on a UCC index.

FIG. 15 illustrates a flow of a method of transmitting and receivingdownlink control information (DCI) according to an embodiment of thepresent invention. FIG. 15 illustrates an example of the aforementionedmethods and, thus, a repeated description of the above description maynot be given here.

Referring to FIG. 15, a base station may transmit information onreference SCS among numerologies of a plurality of subcarrier spacing(SCS) (1505). Information on the reference SCS may be transmitted viahigher layer signaling.

The base station may generate DL control information includinginformation on a slot format (1510).

The base station may transmit DL control information to a UE groupincluding a UE through a UE group common physical downlink controlchannel (PDCCH) (1515).

The UE may acquire information on a slot format from the DL controlinformation (1520).

The DL control information may indicate a slot format based on thereference SCS. When the SCS of the UE is different from the referenceSCS, the UE may convert a slot format of the reference SCS according tothe SCS of the UE.

Time duration of 1 slot may be variable depending on SCS. The referenceSCS may be configured to be equal to or less than the SCS of the UE insuch a way that time duration of 1 slot based on the reference SCS isequal to or greater than time duration of 1 slot based on the SCS of theUE.

When the SCS of the UE is M times the reference SCS, the UE mayinterpret 1 slot based on the reference SCS as M contiguous slots basedon the SCS of the UE.

The UE may determine, based on the information on the slot format,whether each of a plurality of symbols included in the correspondingslot corresponds to downlink (D), uplink (U) or flexible (X). When theSCS of the UE is M times the reference SCS, the UE may interpret one D,U, or X symbol based on the reference SCS as M number of D, U, or Xsymbols based on the SCS of the UE.

Information on a slot format may indicate at least one of slot formationcombinations configured in the UE.

A plurality of frequency bands may be configured for the UE and eachslot format combination may be obtained by combining a plurality of slotformats for a plurality of frequency bands.

Each slot format combination may be obtained by combining a slot formatfor a DL frequency band and a slot format for an UL frequency band.Alternatively, each slot format combination may be obtained by combininga slot format for a new radio access technology (NR) frequency band anda slot format for a long-term evolution (LTE) frequency band.

Slot format combinations configured for a UE may be received via higherlayer signaling and may be a subset of a plurality of slot formatcombinations supported in a wireless communication system. For example,a slot format of a UL band (e.g., UL BWP) and a slot format of a DL band(e.g., DL BWP) may correspond to one slot format combination.Alternatively, a slot format of a BWP on an NR band and a slot format ofa BWP (e.g., SUL) on an LTE band may correspond to one slot formatcombination. The base station may configure at least one slot formatcombination(s) among a plurality of slot format combinations via RRCsignaling for the UE. Then, the base station may indicate at least oneof slot format combination(s) that is RRC-configured for the UE throughDCI transmitted through the group common PDCCH.

FIG. 16 is a block diagram illustrating a structure of a base station(BS) 105 and a UE 110 in a wireless communication system 100 accordingto an embodiment of the present invention. The BS 105 may be referred toas an eNB or a gNB. The UE 110 may be referred to a user terminal.

Although one BS 105 and one UE 110 are illustrated for simplifying thewireless communication system 100, the wireless communication system 100may include one or more BSs and/or one or more UEs.

The BS 105 may include a transmission (Tx) data processor 115, a symbolmodulator 120, a transmitter 125, a transmission/reception antenna 130,a processor 180, a memory 185, a receiver 190, a symbol demodulator 195,and a reception (Rx) data processor 197. The UE 110 may include a Txdata processor 165, a symbol modulator 170, a transmitter 175, atransmission/reception antenna 135, a processor 155, a memory 160, areceiver 140, a symbol demodulator 155, and an Rx data processor 150. InFIG. 12, although one antenna 130 is used for the BS 105 and one antenna135 is used for the UE 110, each of the BS 105 and the UE 110 may alsoinclude a plurality of antennas as necessary. Therefore, the BS 105 andthe UE 110 according to the present invention support a Multiple InputMultiple Output (MIMO) system. The BS 105 according to the presentinvention can support both a Single User-MIMO (SU-MIMO) scheme and aMulti User-MIMO (MU-MIMO) scheme.

In downlink, the Tx data processor 115 receives traffic data, formatsthe received traffic data, codes the formatted traffic data, interleavesthe coded traffic data, and modulates the interleaved data (or performssymbol mapping upon the interleaved data), such that it providesmodulation symbols (i.e., data symbols). The symbol modulator 120receives and processes the data symbols and pilot symbols, such that itprovides a stream of symbols.

The symbol modulator 120 multiplexes data and pilot symbols, andtransmits the multiplexed data and pilot symbols to the transmitter 125.In this case, each transmission (Tx) symbol may be a data symbol, apilot symbol, or a value of a zero signal (null signal). In each symbolperiod, pilot symbols may be successively transmitted during each symbolperiod. The pilot symbols may be an FDM symbol, an OFDM symbol, a TimeDivision Multiplexing (TDM) symbol, or a Code Division Multiplexing(CDM) symbol.

The transmitter 125 receives a stream of symbols, converts the receivedsymbols into one or more analog signals, and additionally adjusts theone or more analog signals (e.g., amplification, filtering, andfrequency upconversion of the analog signals), such that it generates adownlink signal appropriate for data transmission through an RF channel.Subsequently, the downlink signal is transmitted to the UE through theantenna 130.

Configuration of the UE 110 will hereinafter be described in detail. Theantenna 135 of the UE 110 receives a DL signal from the BS 105, andtransmits the DL signal to the receiver 140. The receiver 140 performsadjustment (e.g., filtering, amplification, and frequencydownconversion) of the received DL signal, and digitizes the adjustedsignal to obtain samples. The symbol demodulator 145 demodulates thereceived pilot symbols, and provides the demodulated result to theprocessor 155 to perform channel estimation.

The symbol demodulator 145 receives a frequency response estimationvalue for downlink from the processor 155, demodulates the received datasymbols, obtains data symbol estimation values (indicating estimationvalues of the transmitted data symbols), and provides the data symbolestimation values to the Rx data processor 150. The Rx data processor150 performs demodulation (i.e., symbol-demapping) of data symbolestimation values, deinterleaves the demodulated result, decodes thedeinterleaved result, and recovers the transmitted traffic data.

The processing of the symbol demodulator 145 and the Rx data processor150 is complementary to that of the symbol modulator 120 and the Tx dataprocessor 115 in the BS 205.

The Tx data processor 165 of the UE 110 processes traffic data inuplink, and provides data symbols. The symbol modulator 170 receives andmultiplexes data symbols, and modulates the multiplexed data symbols,such that it can provide a stream of symbols to the transmitter 175. Thetransmitter 175 obtains and processes the stream of symbols to generatean uplink (UL) signal, and the UL signal is transmitted to the BS 105through the antenna 135. The transmitter and the receiver of UE/BS canbe implemented as a single radio frequency (RF) unit.

The BS 105 receives the UL signal from the UE 110 through the antenna130. The receiver processes the received UL signal to obtain samples.Subsequently, the symbol demodulator 195 processes the symbols, andprovides pilot symbols and data symbol estimation values received viauplink. The Rx data processor 197 processes the data symbol estimationvalue, and recovers traffic data received from the UE 110.

A processor 155 or 180 of the UE 110 or the BS 105 commands or indicatesoperations of the UE 110 or the BS 105. For example, the processor 155or 180 of the UE 110 or the BS 105 controls, adjusts, and managesoperations of the UE 210 or the BS 105. Each processor 155 or 180 may beconnected to a memory unit 160 or 185 for storing program code and data.The memory 160 or 185 is connected to the processor 155 or 180, suchthat it can store the operating system, applications, and general files.

The processor 155 or 180 may also be referred to as a controller, amicrocontroller), a microprocessor, a microcomputer, etc. In themeantime, the processor 155 or 180 may be implemented by various means,for example, hardware, firmware, software, or a combination thereof. Ina hardware configuration, methods according to the embodiments of thepresent invention may be implemented by the processor 155 or 180, forexample, one or more application specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, microcontrollers,microprocessors, etc.

In a firmware or software configuration, methods according to theembodiments of the present invention may be implemented in the form ofmodules, procedures, functions, etc. which perform the above-describedfunctions or operations. Firmware or software implemented in the presentinvention may be contained in the processor 155 or 180 or the memoryunit 160 or 185, such that it can be driven by the processor 155 or 180.

Radio interface protocol layers among the UE 110, the BS 105, and awireless communication system (i.e., network) can be classified into afirst layer (L1 layer), a second layer (L2 layer) and a third layer (L3layer) on the basis of the lower three layers of the Open SystemInterconnection (OSI) reference model widely known in communicationsystems. A physical layer belonging to the first layer (L1) provides aninformation transfer service through a physical channel. A RadioResource Control (RRC) layer belonging to the third layer (L3) controlsradio resources between the UE and the network. The UE 110 and the BS105 may exchange RRC messages with each other through the wirelesscommunication network and the RRC layer.

The above-mentioned embodiments correspond to combinations of elementsand features of the present invention in prescribed forms. And, it isable to consider that the respective elements or features are selectiveunless they are explicitly mentioned. Each of the elements or featurescan be implemented in a form failing to be combined with other elementsor features. Moreover, it is able to implement an embodiment of thepresent invention by combining elements and/or features together inpart. A sequence of operations explained for each embodiment of thepresent invention can be modified. Some configurations or features ofone embodiment can be included in another embodiment or can besubstituted for corresponding configurations or features of anotherembodiment. And, it is apparently understandable that an embodiment isconfigured by combining claims failing to have relation of explicitcitation in the appended claims together or can be included as newclaims by amendment after filing an application.

While the present invention has been described and illustrated hereinwith reference to the preferred embodiments thereof, it will be apparentto those skilled in the art that various modifications and variationscan be made therein without departing from the spirit and scope of theinvention. Thus, it is intended that the present invention covers themodifications and variations of this invention that come within thescope of the appended claims and their equivalents.

INDUSTRIAL APPLICABILITY

As described above, the present invention may be applied to variouswireless communication systems.

The invention claimed is:
 1. A method performed by a user equipment (UE)configured to operate in a wireless communication system, the methodcomprising: receiving first information regarding a reference subcarrierspacing (SCS); and receiving, through a UE group common-physicaldownlink control channel (PDCCH), downlink control information (DCI)comprising second information regarding a slot format related to thereference SCS, wherein, based on the reference SCS being equal to orless than a first SCS used by the UE, the slot format is applied to acertain number of slots of the first SCS, and wherein the certain numberof the slots are related to a slot of the reference SCS.
 2. The methodof claim 1, wherein the first information is received through a higherlayer signaling.
 3. The method of claim 1, wherein a time duration ofone slot of the reference SCS is equal or greater than a time durationof each of the certain number of the slots of the first SCS.
 4. Themethod of claim 1, wherein the certain number is determined based ondifferences between the reference SCS and the first SCS.
 5. The methodof claim 1, wherein the certain number of the slots of the first SCScomprises the certain number of consecutive slots of the first SCSrelated to the slot of the reference SCS.
 6. The method of claim 5,wherein the slot of the reference SCS comprises a first plurality ofsymbols, wherein each of the certain number of the slots of the firstSCS comprises a second plurality of symbols, wherein the certain numberof consecutive symbols of the first SCS are related to one symbol of thereference SCS, and wherein in a state in which the slot format isapplied to the certain number of the slots, for each of the firstplurality of symbols in the slot of the reference SCS: the symbol of thereference SCS is determined to be related to one of downlink, uplink, orflexible based on the second information; and the certain number of theconsecutive symbols of the first SCS are determined to be related to oneof downlink, uplink, or flexible.
 7. The method of claim 1, wherein thesecond information comprises information regarding at least one slotformat combination configured in the UE.
 8. The method of claim 7,wherein the UE is configured with a plurality of frequency bands; andwherein each of the at least one slot format combination comprises aplurality of slot formats for the plurality of frequency bands.
 9. Themethod of claim 8, wherein each of the at least one slot formatcombination comprises (i) a slot format for a downlink frequency band,and (ii) a slot format for an uplink frequency band, or wherein each ofthe at least one slot format combination comprises (i) a slot format fora new radio access technology (NR) frequency band, and (ii) a slotformat for a long-term evolution (LTE) frequency band.
 10. The method ofclaim 7, wherein the information regarding the at least one slot formatcombination is received through a higher layer signaling, and whereinthe at least one slot format combination is a subset of a plurality ofslot format combinations supported in the wireless communication system.11. A method performed by a base station (BS) configured to operate in awireless communication system, the method comprising: transmitting, to auser equipment (UE), first information regarding a reference subcarrierspacing (SCS); and transmitting, to a UE group comprising the UE througha UE group common-physical downlink control channel (PDCCH), downlinkcontrol information (DCI) comprising second information regarding a slotformat related to the reference SCS, wherein based on the reference SCSbeing equal to or less than a first SCS used by the UE, the slot formatis related to a certain number of slots of the first SCS, and whereinthe certain number of the slots are related to a slot of the referenceSCS.
 12. A user equipment (UE) configured to operate in a wirelesscommunication system, the UE comprising: a transceiver; and at least oneprocessor coupled with the transceiver, wherein the at least oneprocessor is configured to: receive first information regarding areference subcarrier spacing (SCS); and receive, through a UE groupcommon-physical downlink control channel (PDCCH), downlink controlinformation (DCI) comprising second information regarding a slot formatrelated to the reference SCS, wherein, based on the reference SCS beingequal to or less than a first SCS used by the UE, the slot format isapplied to a certain number of slots of the first SCS, and wherein thecertain number of the slots are related to a slot of the reference SCS.13. A base station (BS) configured to operate in a wirelesscommunication system, the BS comprising: a transceiver; and at least oneprocessor coupled with the transceiver, wherein the at least oneprocessor is configured to: transmit, to a user equipment (UE), firstinformation regarding a reference subcarrier spacing (SCS); andtransmit, to a UE group comprising the UE through a UE groupcommon-physical downlink control channel (PDCCH), downlink controlinformation (DCI) comprising second information regarding a slot formatrelated to the reference SCS, wherein based on the reference SCS beingequal to or less than a first SCS used by the UE, the slot format isrelated to a certain number of slots of the first SCS, and wherein thecertain number of the slots are related to a slot of the reference SCS.